Common problems in SMT chip processing?

Common problems in SMT patch processing?

Common problems with tin beading in SMT chip processing and soldering technology: insufficient preheating of PCB board during reflow soldering; unfair setting of reflow soldering temperature curve, board surface temperature and soldering area temperature before entering the soldering area There is a large interval; the solder paste is not able to fully return to room temperature when it is taken out of the cold storage; the solder paste is exposed to the air for a long time after it is opened; the tin powder splashes on the PCB surface during the patch; printing or During the transfer process, there is oil or water sticking to the PCB board; the distribution of the flux itself in the solder paste is not fair, and there are solvents that are not easy to evaporate or liquid additives or activators.

　　 The first and second reasons above can also clarify why the newly replaced solder paste is prone to such questions. The main reason is that the currently set temperature profile does not match the solder paste used.

The third, fourth, and sixth reasons can be caused by improper manipulation by the user; the fifth reason can be caused by the improper storage of the solder paste or the failure of the solder paste after the expiration date. The solder paste is non-sticky or too sticky. Low, forming a splash of tin powder during placement; the seventh reason is formed by the solder paste supplier’s own production technology.

There are more residues on the board surface after SMT soldering: there are more residues on the PCB board surface after soldering, which is also a question that customers often report. The existence of more residues on the board surface affects the brightness of the board surface. It also has an inevitable impact on the electrical properties of the PCB itself; the main reasons for the formation of more residues are as follows: when the solder paste is implemented, the customer's board conditions and customer needs are not known, or other reasons caused by the wrong selection ; The rosin resin content in the solder paste is too much or its quality is not good.